Hitherto, a method of applying mefentrifluconazole has been known, as a method for controlling a plant pathogen on corn (see Patent Document 1). Also, various types of corn such as field corn, sweet corn, popcorn, and waxy corn are known (see Non-Patent Documents 1, 2). However, it is not known that field corn, especially, can be safely protected from damage by a plant pathogen by applying mefentrifluconazole at certain application rate.